Hello, I've been testing a Pentax 67 kit. I'm very much enjoying the lens selection that came with it, mostly wide angles, which I don't usually get to play with. Problem is, there is a consistent defect in the negatives I'm processing. About 9mm from the right hand side of the neg there is a thin white line. It prints as black. It's on every neg, on multiple rolls. You can see it on the following photo: Any guesses as to what it is, and how the problem can be addressed? Thank you!